Dear Emmanuel —

Let me answer your last question first as it is very important to understand that Baptism and Confirmation are Sacraments that are only done once, as they give a fullness of Grace and do not need to be repeated. In fact it would be offensive to repeat them.

As to what needs to be done for your wedding. The priest at your Church of Baptism needs to send a newly made out Baptism record directly to the priest who is preparing you for Marriage. The priest should not give it to you (to give to the priest) unless this is the only convenient way to travel. It should be in a sealed envelope.

If there is no record of it (which is unlikely for a parish in the United Kingdom) then two people can testify by filling out affidavits in front of a priest as to your Baptism and freedom to marry.

Only if there is doubt about the existence of your Baptism (not just that a record can't be found) or of validity of your Baptism then a conditional baptism would take place but this is rare and probably not the case here, as you certainly know that you have been baptized.

Fr. Jonathan